The disclosed embodiments relate generally to applications wherein a solder is used as an interconnect, and, more particularly, to systems and methods to restrict flow of solder from protected areas in such applications.
Generally, a low melting point filler material such as a solder is used as a joining material or an interconnect between metal components in various applications. For example, in mass production of electronic circuit boards, soldering machines have been developed of a standing wave type wherein a conveyor system carries the circuit boards with electrical components disposed therein over a standing wave of molten solder. The solder fills voids between the electrical components to be joined on the circuit board and completes all of the soldering operations in one pass of the board through the standing wave of solder. However, it is desirable to avoid contact of other components in the circuit board with the solder wave and prevent unwanted wetting of the components in a soldering process.
Solder masks are typically made of an organic material and configured to expose areas that are to be soldered and areas that are to be protected. The thickness of such a mask typically varies from about twenty five microns to about fifty microns and introduces a step between a solderable surface and a protected surface. However, the step is undesirable in certain applications since the step may act as a stress concentrator at locations wherein a joint of the solder deforms around the step. Further, typical organic solder masks cannot withstand temperatures higher than about 200 degrees Celsius for extended periods of time.
Accordingly, an improved technique is needed to address one or more of the foregoing issues.